Materials Science Research & Innovations

Canned Soup Makes BPA Levels Jump

Bisphenol A (BPA) levels in people can rise by 1,221% after eating canned soup compared with fresh soup, according to a first-of-its-kind study.

BPA has been used since the 1950s to make polymer products including liners for food cans, drinking containers, thermal register receipts, DVDs, and car parts. Only recently have researchers raised questions about the chemical’s safety. BPA has been described as an endocrine-disruptor and linked to maladies ranging from diabetes to cancer. The U.S. has urged manufacturers to stop using BPA, and Canada declared BPA as toxic in 2010.

The study — the first to measure how much BPA is absorbed by eating canned food — found some of the highest recorded levels of BPA in urine outside of manufacturing facilities where BPA is used. ‘We were surprised,’ says [researcher Jenny Carwile, a doctoral student in epidemiology at the Harvard School of Public Health]. ‘Other studies have quantified the amount of BPA in canned food itself, so we were expecting a modest association. But this is really big.’

Although the study, published in the Journal of the American Medical Association, looked only at canned soup, the results likely apply to other canned foods and beverages as well.

Carwile and her colleagues examine how much BPA in food packaging gets into humans. For this study, they focused on BPA in canned foods. They recruited 75 fellow students and staff members. Half of the participants ate one 12-oz. can of vegetarian soup each day for five days, while the other half ate soup made from fresh ingredients. After a two-day soup break, they switched. Carwile told Park that the switch ensured that whatever else the participants were eating during the two-week study wouldn’t affect their BPA levels, since the only thing that changed was the source of their soup.

Participants gave urine samples after each soup-eating period so that the researchers could measure BPA levels. Park summarized the results:

In the fresh-soup group, average levels of urinary BPA were about 1.1 micrograms per liter, roughly equivalent to what’s seen in the average American adult. After five days of eating canned soup, however, those levels rose to 20.8 mcg per liter, a more than 1,000% increase.

The American Chemistry Council contends that BPA flushes out of the body quickly, and only massive exposure has been conclusively determined to be harmful, writes Lesley Ciarula Taylor, staff reporter for the Toronto Star. The council has also said that without BPA, Taylor writes, inexpensive and convenient canned foods and plastic goods would not exist.

Rachel Petkewich is a freelance science writer and editor. She has worked as a research scientist in the chemical industry and spent eight years as a staff writer and editor at various science journals and magazines, including Chemical & Engineering News.